Johnson’s Flower and Garden Center
Pest Bulletin #2

 

AZALEA LACE BUG

(Stephanitis pyrioides)

 

How to Identify Damage

Lace bugs feed on the undersides of leaves and produce yellowish flecks on the upper leaf surface.  The yellow mottling is in a large number of contiguous cells, giving a stippled appearance to the plant. The presence of brown varnish-like droplets of excrement on the underside of the leaf is certain confirmation of lace bug presence.

 

Life Cycle

Lace bugs overwinter on broadleaf evergreens as eggs. The eggs are attached to the leaves and resemble brown cones partially embedded in the leaf surface near mid-vein. In the District of Columbia and Maryland, the eggs begin hatching in late April to late May. Nymphs are mostly black in color and have numerous spines, especially along the posterior end. Four generations are produced throughout the growing year. The adults are about 1/8 inch long with transparent wings. The segmentation of the wings makes them resemble stained glass window divisions or even lace. Development from nymph to adult takes about one month.

 

Critical Control Time

The time for control is when the damage is first noticed on the affected plants. Stippling of host plants usually begins on the older leaves inside the contour of the plant, so focus your attention there as well as on plants in sunny areas. You should decide whether the amount of damage merits use of controls, particularly if the plant is in a semi-shady area.

 

Control Strategies

Lace bug damage is usually most prevalent on plants in a sunny area and is usually limited on plants grown in the shade. A natural predator that operates in the shade is suspected to exist. Therefore, planting azaleas in semi-shade to shade is a good way to minimize lace bug problems. To control existing infestations, use horticultural oil (also known as dormant oil) or horticultural soaps according to the label. Remember that lace bugs can have four generations a year, so even if you eliminate them once, they can reinfest your plant later in the year. You must monitor the plant throughout the growing season to find signs of developing or recurring problems.

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